Commit 83e3c487 authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Ingo Molnar
Browse files

mm/sparsemem: Allocate mem_section at runtime for CONFIG_SPARSEMEM_EXTREME=y 



Size of the mem_section[] array depends on the size of the physical address space.

In preparation for boot-time switching between paging modes on x86-64
we need to make the allocation of mem_section[] dynamic, because otherwise
we waste a lot of RAM: with CONFIG_NODE_SHIFT=10, mem_section[] size is 32kB
for 4-level paging and 2MB for 5-level paging mode.

The patch allocates the array on the first call to sparse_memory_present_with_active_regions().

Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@suse.de>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170929140821.37654-2-kirill.shutemov@linux.intel.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 96753522

include/linux/mmzone.h

+5 −1
Original line number Diff line number Diff line
@@ -1150,13 +1150,17 @@ struct mem_section { 
#define SECTION_ROOT_MASK	(SECTIONS_PER_ROOT - 1)



#ifdef CONFIG_SPARSEMEM_EXTREME

extern struct mem_section *mem_section[NR_SECTION_ROOTS];

extern struct mem_section **mem_section;

#else

extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];

#endif



static inline struct mem_section *__nr_to_section(unsigned long nr)

{

#ifdef CONFIG_SPARSEMEM_EXTREME

	if (!mem_section)

		return NULL;

#endif

	if (!mem_section[SECTION_NR_TO_ROOT(nr)])

		return NULL;

	return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];

mm/page_alloc.c

+10 −0
Original line number Diff line number Diff line
@@ -5646,6 +5646,16 @@ void __init sparse_memory_present_with_active_regions(int nid) 
	unsigned long start_pfn, end_pfn;

	int i, this_nid;



#ifdef CONFIG_SPARSEMEM_EXTREME

	if (!mem_section) {

		unsigned long size, align;



		size = sizeof(struct mem_section) * NR_SECTION_ROOTS;

		align = 1 << (INTERNODE_CACHE_SHIFT);

		mem_section = memblock_virt_alloc(size, align);

	}

#endif



	for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, &this_nid)

		memory_present(this_nid, start_pfn, end_pfn);

}

mm/sparse.c

+11 −6
Original line number Diff line number Diff line
@@ -22,8 +22,7 @@ 
 * 1) mem_section	- memory sections, mem_map's for valid memory

 */

#ifdef CONFIG_SPARSEMEM_EXTREME

struct mem_section *mem_section[NR_SECTION_ROOTS]

	____cacheline_internodealigned_in_smp;

struct mem_section **mem_section;

#else

struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]

	____cacheline_internodealigned_in_smp;
@@ -100,7 +99,7 @@ static inline int sparse_index_init(unsigned long section_nr, int nid) 
int __section_nr(struct mem_section* ms)

{

	unsigned long root_nr;

	struct mem_section* root;

	struct mem_section *root = NULL;



	for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {

		root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
@@ -111,7 +110,7 @@ int __section_nr(struct mem_section* ms) 
		     break;

	}



	VM_BUG_ON(root_nr == NR_SECTION_ROOTS);

	VM_BUG_ON(!root);



	return (root_nr * SECTIONS_PER_ROOT) + (ms - root);

}
@@ -329,11 +328,17 @@ again: 
static void __init check_usemap_section_nr(int nid, unsigned long *usemap)

{

	unsigned long usemap_snr, pgdat_snr;

	static unsigned long old_usemap_snr = NR_MEM_SECTIONS;

	static unsigned long old_pgdat_snr = NR_MEM_SECTIONS;

	static unsigned long old_usemap_snr;

	static unsigned long old_pgdat_snr;

	struct pglist_data *pgdat = NODE_DATA(nid);

	int usemap_nid;



	/* First call */

	if (!old_usemap_snr) {

		old_usemap_snr = NR_MEM_SECTIONS;

		old_pgdat_snr = NR_MEM_SECTIONS;

	}



	usemap_snr = pfn_to_section_nr(__pa(usemap) >> PAGE_SHIFT);

	pgdat_snr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);

	if (usemap_snr == pgdat_snr)

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